The present invention relates generally to electric or pneumatic power drivers.
Electric and pneumatic tool drivers are well known. Although twist drills are the most common tools on such drivers, the tools may also comprise screw drivers, nut drivers, burrs, mounted grinding stones and other cutting or abrading tools. Since the tool shanks may be of varying diameter or of polygonal cross section, the device is usually provided with a chuck that is adjustable over a relatively wide range. The chuck may be attached to the driver spindle by a threaded or tapered bore.
A variety of chucks for both hand and power drivers have been developed in the art. In one form of chuck, a chuck body includes three passageways disposed approximately 120 degrees apart from each other. The passageways are configured so that their center lines meet at a point along the chuck axis that is typically forward of the chuck. The passageways constrain three jaws which are moveable in the passageways to grip a cylindrical or polygonal tool shank displaced approximately along the chuck""s center axis. The chuck includes a nut that rotates about the chuck center and that engages threads on the jaws so that rotation of the nut moves the jaws in either direction within the passageways. The body is attached to the spindle of a driver and is configured so that rotation of the body in one direction with respect to the nut forces the jaws into a gripping relationship with the tool shank, while rotation in the opposite direction releases the gripping relationship.
The chuck may be operated by a chuck key, by hand rotation of the sleeve in a keyless configuration, or by actuation of the driver motor. A keyless chuck may include a rear sleeve axially and rotationally held to the chuck body to permit an operator to rotationally hold the chuck body while rotating the chuck nut to open and close the chuck jaws. An example of a keyless chuck is disclosed in U.S. Pat. No. 5,501,473, which is commonly assigned and the entire disclosure of which is incorporated by reference herein.
Various configurations of keyless chucks are known in the art and are desirable in a variety of applications. For example, in one known form of a drill chuck, a rear sleeve is rotationally fixed to a spring-biased impact member that slides axially within the rear sleeve and that can selectively hold the nut against rotation with respect to the rear sleeve. Thus, when the drill spindle rotationally drives the chuck body, relative rotation between the body and the restrained nut drives the jaws toward an open or closed position.
To rotationally restrain the nut, however, the chuck also includes a mechanism to rotationally restrain the rear sleeve with respect to the drill housing. Specifically, a pair of screw heads extend forward from the front face of the drill on opposite sides of the drill spindle. A pair of legs that are rotationally fixed to, but axially movable with respect to, the rear sleeve extend rearwardly through the rear sleeve and receive the screw heads so that the screw heads rotationally hold the legs and the rear sleeve to the drill housing.
The legs are spring-biased rearwardly from the rear sleeve. As the drill spindle and the chuck body thread together, and therefore move axially toward each other, the front drill face pushes the legs forwardly into the chuck. The increased spring pressure increases the hold of the legs about the screw heads.
The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.
Accordingly, it is an object of the present invention to provide an improved chuck assembly and power driver.
It is also an object of the present invention to provide an improved interface between a chuck assembly and a power driver.
These and other objects are accomplished by providing a chuck assembly for use with a power driver having a forward end, a housing, a gearbox, and a rotating spindle extending therefrom that includes a separate interface plate. The interface plate is received by and is rotationally fixed to the forward end and includes a forward face defining a center opening and a forwardfacing rotational stop. The spindle extends through the center opening to receive a chuck. The chuck includes a body having a nose and a tail, the tail being configured to rotate with the spindle and the nose including an axial bore. Chuck jaws are received by the body and movable toward and away from the chuck axis. A bracket is disposed about the body and extends rearward of the tail. The bracket defines a rearward surface engaging the stop to rotationally fix the bracket to the interface plate.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention.